中更新世以来不同时间尺度亚洲中纬度气候演化的区域差异

The regional difference of climate evolution across mid-latitude Asia since mid-Pleistocene

亚洲中纬度气候主要受两大环流控制,继而划分出受亚洲季风控制季风区和受西风环流控制的西风区。已有研究发现在年代际至千年尺度上,两气候区的湿度演化存在错相位、甚至反相位的现象。文章综述了中更新世以来,多千年至轨道尺度上,两气候区的湿度演化模态的异同,以此深入了解亚洲气候演化的系统性。结果表明:二者的间冰期气候演化的整体趋势存在明显差别,尤其MIS 13以来,二者的演化趋势基本相反。在间冰期的多千年至万年尺度上,二者的气候演化模态呈现非同相位:高精度的释光测年结果显示天山地区的湿度变化滞后于黄土高原地区大概3~5 ka,且该现象在更早的间冰期可重复。在冰期的千年尺度上,两地的湿度演化基本一致,但西风区湿度的波动幅度更大。

The Asia monsoon and westerly are two most important atmosphere circulations in mid-latitude Asia, which climatically dominate Eastern Asia and Central Asia. The previous study discovered the moisture of these two regions varied out-of-phase on multiple scales, from decades to millennium, in the Holocene. Here we investigated their relationships from millenniums to orbital scales since mid-Pleistocene by reviewed our studies recently. The Tajikistan loess is a high-resolution record which documented the climate change since 1.8 Ma. The DK section(38°23'04"N, 69°50'01"E) recorded the climate is humid in the interglacials and arid in the glacials in Central Asia, the pattern of which is similar with Chinese Loess Plateau(CLP) loess record(XF section:35°46'N, 107°41'E). However, by comparison the interglacial climate variation pattern on long time scale, it can be discovered the out-of-phase or anti-phase pattern of climate variations between Central Asia and CLP. The cycle analysis investigation further revealed the weak obliquity cycle and strong precession cycle being recorded by Tajikistan loess contrasting CLP loess. On millenniums scales, the climate variation also exhibited an out-of-phase pattern between Central Asia and CLP during interglacials. The magnetic proxies, combing with OSL dating, from several sections, presented a dry Early Holocene, moderate mid-Holocene, and humid Late Holocene pattern in Central Asia, and a dry Early Holocene, humid mid-Holocene, and dry Late Holocene in CLP. In comparison, the climate change in central Asia lagged about 3~5 ka. The similar phenomenon also can be detected in last interglacial. We further compared the climate change during glacials. The last glacial record from DK section presented several obvious millennium climate events which were corresponding with D-O events. They exhibited humid climate during warm stages and arid climate during cold stages, the pattern was same to that in CLP, but the events were more intensive. From loess records, it can be concluded that the climate change between Central Asia and CLP presents an out-of-phase pattern during interglacials from millenniums to orbital scales since mid-Pleistocene, but in-phase during glacials. We had poor understand of the climate evolution forcing mechanism in the region. More climate modeling investigations need to developing in the future.